Many combustion engines utilize conventional spark plugs for igniting fuel in a piston chamber. FIG. 1 illustrates a spark plug ignition terminal system known to those skilled in the art. A conventional spark plug includes a central electrode 10 a portion of which is covered with a ceramic insulator 12. A first end 14 extends outwardly from the ceramic insulator 12 and is spaced a distance from a ground electrode 16. A second end 18 has a terminal post 20 thereon. The terminal post includes an annular groove 22 formed on an outer surface adjacent a terminal engagement head 24. A threaded metal housing 26 may surround a portion of the ceramic insulator 12 and includes a hex nut feature 28 for tightening the spark plug into a threaded bore of an engine. The prior art ignition terminal includes a first end including crimp wings 30 for crimping onto an ignition wire 32. A second end of the terminal includes a terminal barrel formed by converging tabs 34. The tabs 34 butt up against each other in an unconnected relation. A snap ring 36 is placed around the terminal barrel and includes raised features at opposed ends. As shown in FIG. 2, each raised feature 38 extends through an aperture 40 formed in tab 34 defining the terminal barrel and so that the raised features 38 are received in the annular groove 22 formed in the terminal post 20.
Notwithstanding the use of the snap ring 36, the prior art terminal barrel tabs 34 can spread open under certain circumstances. The barrel tabs 34 can be opened with relatively little force applied to the converging tabs in a direction perpendicular to the spark plug terminal axis (or to the longitudinal axis of the terminal barrel). For example, the barrel tabs are often opened by repeated terminal engagements and removal that applies side-loading. That is, by not engaging or pulling the terminal off the spark plug in a direction parallel to the longitudinal axis of the terminal barrel.
Although terminals having barrels formed from interlocking tabs are known, these terminals still suffer from this side-loading phenomenon. In fact, the use of interlocking tabs makes the side-loading problem worse because once the interlocking tabs are opened by side-loading they are much more difficult to properly put back together.
The present invention provides advantages over and alternatives to the prior art ignition terminal systems.